Hopkins Marine Station Student Paper

Title: Behavior of the wrack dipterans Fucellia rufitibia (Anthomyiidae), Coelopa vanduzeei (Coelopidae), and Leptocera johnsoni (Sphaeroceridae) on a California beachStudent Author(s): Hyatt, Joel D.Faculty Advisor(s): Abbott, DonaldPages: 26Location: Final Papers Biology 175HDate: June 1972 Keywords: sandy beachesAbstract: The beach wrack flies Fucellia rufitibia, Coelopa vanduzeei, and Leptocera johnsoni occupy successive vertical levels inside banks of mixed wrack found low on California beaches. When the wrack is washed away, Coelopa are then found at the sand-wrack flake interface with Leptocera; Fucellia in a black band of flies above the highest waterline. Fucellia range widely up and down the beach. Movement to higher beach positions at night seems to be associated with temperature, but some Fucellia remain in the warmer surface layers of the lower wrack banks at night. Coelopa are usually only found at lower beach positions where they inhabit the moist intertior of wrack banks. Moisture and tide level are the important factors in Coelopa behavior. Mark and release experiments show that F. rufitibia do not disperse widely but constitute more or less fixed communities on the beach. C. vanduzeei are gregarious. In wrack preference experiments in the field, Fucellia and Coelopa exhibit strong preference for the surf grass Phyllospadix, probably as a source of shelter. Brown algae and mixed wrack are preferred to the same degree; red algae very little.